Synthesis, Characterization, and Processing of Highly Bioadhesive Polyurethane Urea as a Microfibrous Scaffold Inspired by Mussels

The need to obtain solid adhesive scaffolds that can be processed to create friendly microenvironments, direct cellular behaviors, and tissue regeneration is growing. A facile method was used to incorporate a mussel-inspired adhesive moiety, dopamine, into segmented polyurethanes based on polycaprolactone-polyethylene glycol-polycaprolactone (PCL-PEG-PCL) copolymers. Dopamine was chemically bonded to lysine and used as a chain extender to obtain a solid biodegradable elastomer capable of strongly adhering to different materials after melting occurs. Lysine alone was used as a chain extender to produce a similar polyurethane control group. The low melting point (55 degrees C) opens multiple possible applications for this polyurethane. A complete chemical-physical characterization was performed, and adhesion strength was evaluated in a lap shear configuration. The interaction with a high-energy surface like glass and aluminum at room temperature was remarkable (respectively 2.8 and 2.6 MPa). The adhesion was also evaluated with porcine skin underwater at 37 degrees C, resulting in 30 kPa. Over a period of 6 months, the material undergoes slow hydrolytic degradation. Nevertheless, the material and its degradation products were not cytotoxic. The polymer was then processed with melt extrusion three-dimensional (3D) printing to obtain oriented microfibers, producing different scaffolds.